Witt

OK, this is slightly off topic because this isn't a question necessarily about Scions but you guys that occupy the F/I part of scionlife.com seem to really know your ____, so here goes:

I own a car with a roots type blower stock and we all pretty much max out our wheel hp for the car by dropping pulley sizes/larger injector swaps and methanol injection just shy of 275 whp. The easiest solution to making more power seems to be taking the twincharge/dual charge route. My questions on wanting to build a custom twincharge kit are as follows...

MAF placement. We run a MAF and MAP setup and I could set it up to run only the MAP but I would never pass state emissions, so I have to eventually have a working MAF. Where would be the best place to install it? My understanding is directly after the air filter pre turbo, and use a recirculating valve in place of a atmospheric blow off valve. Is it at all possible to run the MAF post turbo and before the throttle body? I have full control of engine management using HP Tuners, so I can rescale the factory MAF to any frequency, but would it give me consistent readings at levels above one atmosphere of pressure? Also, my MAF sensor has a built in IAT1 sensor as well, so intake temps before the heat exchanger shouldn't be a problem.

Second, being that I have a blower already bolted onto the intake, I need to find a pulley system that will spin the blower at a slower rate than stock to keep my engine in one piece. My question is, at what rate does the blower compress air already above one bar of pressure entering its intake? The way I THINK I have this figured out, baro. pressure is ~14 psi and my stock 3.25" pulley is good for an additional 12 psi above atmospheric, therefor creating 26 total pounds of boost, including atmospheric pressure. The blower created boost as a ratio above atmospheric, theoretically 26/14 or a 1.86 ratio. With a turbo say pushing 5 psi, add that to the atmospheric 14 and it would equal 35.34 psi, obviously too much on my internals. IF my figure is right, thats why I have to come up with a pulley size, turbo combo that will keep my engine from an impending disaster. My question again is, is that figure I have correct? If so, its going to be a little tough to find a pulley/turbo combo and still keep each inside of their efficiency range.

And, in case you were wondering why I posted this here other than my home forums is the simple fact that back there, its getting a little bit childish. Its hard to get an answer from people who aren't acting like 12 year olds let alone know anything about modifying a car in the capacity I plan on doing. You guys here seem a little bit more down to earth and a bit easier on flaming posts so I figured I'd give it a shot. I really hate to start buying parts to put this project together and realize that it simply won't work and have to resell/take a loss on everything I had purchased. Oh yeah, and lastly, this is for a Cobalt SS/SC. Thanks in advance.

yamaha16bw

I'm not going to comment about twincharging cause thats alittle over my head but, I do know that Mini Cooper's guy do some twin charging. Maybe try a mini forum?

Joe_Dezod

I will chime in in a breif way to steer you in the right direction...

I'd contact NST for pulley engineering to have them fab something that could work for the boost level you want on your car. For the turbo part, using a T3/T4 with a .48 AR may be ideal because you're running such low boost. If you go to a larger turbo you may be operating in "surger" and creating way too much heat for that motor. Run with a larger (38mm+) TiAL wastegate to control boost so you don't have boost creep. If you're plumbing it back into the exhaust do it at least 6-8" away from the point for the down pipe connects to your turbo.

As for you MAF... Install the MAF on the air filter pipe, about 2-3" behind your air filter. If you put it on a charge pipe, the temps may be too hot for the sensor and you're probably be replacing the MAF sensor on a regular basis. MAF's only read velocity not pressure, so there's almost no need for it to meter "compressed air", only the speed of the air. That being said, stick to the air filter side, it'll be more accurate and more reliable.

Witt

As far as the pulley goes, Intense Racing sells a 3.6" from an Eaton M90 for the Grand Prix guys that will fit my M62. I think ZZ Performance even sells larger ones than that. The only problem actually is trying to find a tensioner pulley smaller than stock so my belt fits. Everyone makes a larger pulley to take up slack after dropping blower pulley sizes, but a smaller one is kinda unheard of. I'm prolly going to the auto parts store tomorrow to look at a belt from a VR6 GTI and an 92-95 I think LT1 Vette as they should be double sided belts and hopefully they're a bit longer than my stock or GM Stage 2 belt. Double sided ribbed belts for the lose.

The MAF placement is kinda what I though, I just wanted to make sure as its going to be a pain to have to reroute wiring from the drivers side front to passenger side rear of the engine bay, if I didn't have to.

Mase77

I basically have the same car as you (Ion Redline). If your looking for twincharge, then check this out:
http://www.hahnracecraft.com/Project...t/CobaltSS.htm

What are you currently running (injectors, pulley, meth kit, HP Tuners)?

If your looking for a custom pulley, I have a contact that can fabricate one for you.

Magnus213

iTrader: (1)

Update: I was reading the November Super Street that I got today and they provided an update of all of cars in their "garage;" one of them is a red tC with a full carbon fiber body kit, that they plan to twincharge to make 400 hp. You may want to look at that, as vague as it is.

*Edit, went back and looked it up*

"Owner: Auto-Tech Interiors
Hometown: So-Cal
Daily Grind: Grindin'
Future Prospects: twin-charged tC for time attack
Power: estimated 400 hp
Under the Hood: TRD supercharger; HKS GT3040 turbo; GTII wastegate; Racing Type II blow-off valve; EVC boost controller; 1,000cc injectors, turbo timer; Defi gauges; ATI gauge pod
Brains: HKS VPro
Stiff Stuff: TRD sway bars; Tein coilovers
Rollers: Volk Progressive wheels
Stoppers: Stop Tech brake kit
Outside: AIT carbon fiber widebody; Fireball Tim Racing graphics
etc. etc.
Impression: Twin-charged tC? Better believe it. On a mission to make 400 hp out of the Camry-motor equipped Scion, read here to see what happens."

They say the twincharging is a future prospect, but they list the mods with it all there... I guess they're just planning ahead? Oh well, hope that's at least informative / entertaining.

Skunk

I'll chime in on what I know about twin-charging. Basically outside of extremely well-tuned small engine applications it's a waste of time and money. There is really no benefit at all that can't be accomplished easier and cheaper by modifying your existing setup or just upgrading to a larger or more efficient supercharger.

xSTANDxSTRONGx

that (soon-to-be)twincharged tC is sick. If it's the one I'm thinking of, it came to one of the Ontario Mills meets a few months back....DISGUSTING! That w/b kit is off the hook.